Generally speaking the present invention relates to a heating system wherein a flue damper regulates gas flow through a conduit from a heat source in accordance with a temperature demand means actuating the heat source, and more particularly to a controller connected to the flue damper that rotates it 360.degree. in about 90.degree. increments to selectively open and close the damper.
Numerous dampening systems for use in heat and smoke stacks have been proposed and used. Currently in some flue damper systems, for example, hysteresis type motors are used drive a coil spring loaded flue plate against a stop thereby stalling the motor with the plate in a closed position. Then, when a thermostatic switch calls for heat, a relay is pulled in and power to the motor is broken. With the motor deenergized, the coil spring causes the flue plate to open by turning the motor backwards. Then, as the flue comes to a full open position, a switch actuates a gas valve. While such an arrangement is acceptable, it does have some inherent problems. For example, a hysteresis type motor is expensive. The system requires a relatively large number of parts thus adding to fabrication costs. In addition, the use of the coil spring to return the flue to an open position causes inaccuracies with a certain amount of tendency to fail.
In another arrangement a flue damper is connected to a motor to be rotated in accordance with a programmed sequence. The motor is turned on and off through a relay. With this arrangement the use of a relay requires considerable supporting electrical circuitry which makes the system costly and in some respects relatively inaccurate.
The present invention overcomes these problems and in addition provides for other features noted hereinafter.